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Add config to reduce weight on small samples in BitrateEstimator.

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Change #159711 adds the option to filter out small packets on the
input to the delay-based BWE. This change adds similar functionality
to BitrateEstimator by reducing the weight of small observations.

Bug: webrtc:10932
Change-Id: I0a673a067f7ef86769cabd30443e60e9de70053c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/160009
Commit-Queue: Christoffer Rodbro <crodbro@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29865}
This commit is contained in:
Christoffer Rodbro 2019-11-21 15:19:40 +01:00 committed by Commit Bot
parent 63737a918b
commit 58a3210823
2 changed files with 30 additions and 14 deletions
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37
modules/congestion_controller/goog_cc/bitrate_estimator.cc
View File

@ -43,7 +43,9 @@ BitrateEstimator::BitrateEstimator(const WebRtcKeyValueConfig* key_value_config)
kMinRateWindowMs,
kMaxRateWindowMs),
uncertainty_scale_("scale", 10.0),
uncertainty_scale_in_alr_("scale_alr", 10.0),
uncertainty_scale_in_alr_("scale_alr", uncertainty_scale_),
small_sample_uncertainty_scale_("scale_small", uncertainty_scale_),
small_sample_threshold_("small_thresh", DataSize::Zero()),
uncertainty_symmetry_cap_("symmetry_cap", DataRate::Zero()),
estimate_floor_("floor", DataRate::Zero()),
current_window_ms_(0),
@ -51,10 +53,11 @@ BitrateEstimator::BitrateEstimator(const WebRtcKeyValueConfig* key_value_config)
bitrate_estimate_kbps_(-1.0f),
bitrate_estimate_var_(50.0f) {
// E.g WebRTC-BweThroughputWindowConfig/initial_window_ms:350,window_ms:250/
ParseFieldTrial({&initial_window_ms_, &noninitial_window_ms_,
&uncertainty_scale_, &uncertainty_scale_in_alr_,
&uncertainty_symmetry_cap_, &estimate_floor_},
key_value_config->Lookup(kBweThroughputWindowConfig));
ParseFieldTrial(
{&initial_window_ms_, &noninitial_window_ms_, &uncertainty_scale_,
&uncertainty_scale_in_alr_, &small_sample_uncertainty_scale_,
&small_sample_threshold_, &uncertainty_symmetry_cap_, &estimate_floor_},
key_value_config->Lookup(kBweThroughputWindowConfig));
}
BitrateEstimator::~BitrateEstimator() = default;
@ -65,8 +68,9 @@ void BitrateEstimator::Update(Timestamp at_time, DataSize amount, bool in_alr) {
// we can use to initialize the estimate.
if (bitrate_estimate_kbps_ < 0.f)
rate_window_ms = initial_window_ms_.Get();
float bitrate_sample_kbps =
UpdateWindow(at_time.ms(), amount.bytes(), rate_window_ms);
bool is_small_sample = false;
float bitrate_sample_kbps = UpdateWindow(at_time.ms(), amount.bytes(),
rate_window_ms, &is_small_sample);
if (bitrate_sample_kbps < 0.0f)
return;
if (bitrate_estimate_kbps_ < 0.0f) {
@ -74,15 +78,19 @@ void BitrateEstimator::Update(Timestamp at_time, DataSize amount, bool in_alr) {
bitrate_estimate_kbps_ = bitrate_sample_kbps;
return;
}
// Optionally use higher uncertainty for very small samples to avoid dropping
// estimate and for samples obtained in ALR.
float scale = uncertainty_scale_;
if (is_small_sample && bitrate_sample_kbps < bitrate_estimate_kbps_) {
scale = small_sample_uncertainty_scale_;
} else if (in_alr && bitrate_sample_kbps < bitrate_estimate_kbps_) {
// Optionally use higher uncertainty for samples obtained during ALR.
scale = uncertainty_scale_in_alr_;
}
// Define the sample uncertainty as a function of how far away it is from the
// current estimate. With low values of uncertainty_symmetry_cap_ we add more
// uncertainty to increases than to decreases. For higher values we approach
// symmetry.
float scale = uncertainty_scale_;
if (in_alr && bitrate_sample_kbps < bitrate_estimate_kbps_) {
// Optionally use higher uncertainty for samples obtained during ALR.
scale = uncertainty_scale_in_alr_;
}
float sample_uncertainty =
scale * std::abs(bitrate_estimate_kbps_ - bitrate_sample_kbps) /
(bitrate_estimate_kbps_ +
@ -108,7 +116,9 @@ void BitrateEstimator::Update(Timestamp at_time, DataSize amount, bool in_alr) {
float BitrateEstimator::UpdateWindow(int64_t now_ms,
int bytes,
int rate_window_ms) {
int rate_window_ms,
bool* is_small_sample) {
RTC_DCHECK(is_small_sample != nullptr);
// Reset if time moves backwards.
if (now_ms < prev_time_ms_) {
prev_time_ms_ = -1;
@ -126,6 +136,7 @@ float BitrateEstimator::UpdateWindow(int64_t now_ms,
prev_time_ms_ = now_ms;
float bitrate_sample = -1.0f;
if (current_window_ms_ >= rate_window_ms) {
*is_small_sample = sum_ < small_sample_threshold_->bytes();
bitrate_sample = 8.0f * sum_ / static_cast<float>(rate_window_ms);
current_window_ms_ -= rate_window_ms;
sum_ = 0;

7
modules/congestion_controller/goog_cc/bitrate_estimator.h
View File

@ -38,12 +38,17 @@ class BitrateEstimator {
virtual void ExpectFastRateChange();
private:
float UpdateWindow(int64_t now_ms, int bytes, int rate_window_ms);
float UpdateWindow(int64_t now_ms,
int bytes,
int rate_window_ms,
bool* is_small_sample);
int sum_;
FieldTrialConstrained<int> initial_window_ms_;
FieldTrialConstrained<int> noninitial_window_ms_;
FieldTrialParameter<double> uncertainty_scale_;
FieldTrialParameter<double> uncertainty_scale_in_alr_;
FieldTrialParameter<double> small_sample_uncertainty_scale_;
FieldTrialParameter<DataSize> small_sample_threshold_;
FieldTrialParameter<DataRate> uncertainty_symmetry_cap_;
FieldTrialParameter<DataRate> estimate_floor_;
int64_t current_window_ms_;